Technical Field
Embodiments of the present invention relate to an optical sensor, a paper-type discrimination device having the optical sensor, and an image forming apparatus having the paper-type discrimination device.
Background Art
As an optical sensor that irradiates an object to be measured with light, for example, the technology to discriminate the type of paper by measuring the bumps and dips of the surface of the paper, which is provided for image forming apparatuses such as a copier, facsimile (FAX), and a printer, is known in the art. As such a technology used for paper-type discrimination, optical sensors that irradiate paper with light and use the reflection light from the paper to discriminate the type of the paper are known.
In order to discriminate the types of paper with high accuracy using an optical sensor, it is desired that the irradiating point of light be fixed regardless of the type of the paper. For this reason, a configuration is known in the art in which an opening is formed on a plane having a certain angle with reference to the incidence direction of the light and the light reflected from the portion of the plane exposed by the opening is measured.